Light emitting device

Abstract

The invention relates to a light-emitting device ( 1 ) comprising: a light source ( 2 ) for emitting light of a first wavelength range; a light guide ( 3 ) having a light receiving surface ( 4 ) for receiving at least part of said light emitted by the light source ( 2 ), a front surface ( 31 ) and a rear surface ( 32 ), for guiding light of said first wavelength range by total internal reflection at said front surface and said rear surface; a plurality of outcoupling elements ( 5 ) for outcoupling light from the light guide such that at least part of the light that is outcoupled by the outcoupling elements exits the light guide through said rear surface; a reflective member ( 6 ) arranged in rear of said light guide to reflect light that is outcoupled from the light guide; and a wavelength converting member ( 8 ) comprising a wavelength converting material arranged outside the light guide to convert light of said first wavelength range to light of a second wavelength range. Advantageously, in the light-emitting device according to the invention, the color, color temperature and/or color rendering index may be tuned by modifying the wavelength converting member. As a result, white light which is perceived as warm may be obtained.

1 . Light-emitting device comprising:
 a light source for emitting light of a first wavelength range;   a light guide having
 a light receiving surface for receiving at least part of said light emitted by the light source, 
 a front surface and 
 a rear surface, for guiding light of said first wavelength range by total internal reflection at said front surface and said rear surface; 
   a plurality of outcoupling elements for outcoupling light from the light guide such that at least part of the light that is outcoupled by the outcoupling elements exits the light guide through said rear surface;   a reflective member arranged in rear of said light guide to reflect light that is outcoupled from the light guide; and   a wavelength converting member comprising a wavelength converting material arranged outside the light guide to convert light of said first wavelength range to light of a second wavelength range.   
     
     
         2 . Light-emitting device according to  claim 1 , wherein said reflective member is diffusive. 
     
     
         3 . Light-emitting device according to  claim 1 , wherein said wavelength converting member and said reflective member are provided on different sides of the light guide. 
     
     
         4 . Light-emitting device according to  claim 1 , wherein said wavelength converting member is provided in front of the light guide. 
     
     
         5 . Light-emitting device according to  claim 1 , wherein said wavelength converting material is arranged in the path of light from said light guide to said reflective member. 
     
     
         6 . Light-emitting device according to  claim 5 , wherein said wavelength converting material is arranged on said reflective member. 
     
     
         7 . Light-emitting device according to  claim 1 , wherein said wavelength converting member comprises a plurality of discrete domains comprising wavelength converting material. 
     
     
         8 . Light-emitting device according to  claim 5 , wherein said wavelength converting member comprises a continuous layer comprising a wavelength converting material. 
     
     
         9 . Light-emitting device according to  claim 1 , wherein said plurality of outcoupling elements is provided on an outer surface of the light guide. 
     
     
         10 . Light-emitting device according to  claim 1 , wherein said plurality of outcoupling elements are provided on said front surface of the light guide. 
     
     
         11 . Light-emitting device according to any one of the preceding claims, wherein said outcoupling elements comprise a scattering material. 
     
     
         12 . Light-emitting device according to  claim 1 , wherein the coverage of said front surface by the outcoupling elements increases with the distance from the light receiving surface along the light guide. 
     
     
         13 . Light-emitting device according to  claim 1 , wherein the light source ( 2 ) comprises at least one light-emitting diode. 
     
     
         14 . Light guide, comprising a light receiving surface for receiving light, a front surface and a rear surface, for guiding light of a first wavelength range by total internal reflection at said front surface and said rear surface, and further comprising a plurality of outcoupling elements for outcoupling light from the light guide through said rear surface, wherein said light guide is as defined in  claim 1 .